In the field of skin care, many serums, moisturizers and specific conditioning formulations are available. Additionally, many medications are designed for topical application to the skin. It is known to apply a wide range of skin care and treatment products with either general purpose or application-specific applicator tools. Generally, available applicators only provide means for applying a liquid in contact with the skin, and/or some type of reservoir for supplying the portion of the applicator that makes contact with the skin. The inventors have observed that the applicators available in the art are not designed to promote reactions, e.g., electro-chemically, or thermo-chemically, etc., as a compliment to physically applying a liquid in contact with the skin. An additional problem with known skin applicators is that they do not provide feedback to the user as to the condition of the skin or the underlying tissue. Also, skin features such as blemishes, dark spots, and wrinkles are not detected, differentiated, or monitored to provide accurate diagnosis and tracking of a user's skin characteristics. Due to these and other problems and potential problems, novel and useful apparatus has been invented for the application of skin care products, including cleansing, cosmetic, and medical products, that include features for promoting interactions between the applied product and the skin, and which can be beneficial in improving skin and underlying tissue health.